Animal Production and Health Division, FAO Headquaters,
Vialle delle Terme di Caracalla,
00100, Rome, Italy.
Traditional livestock production, either in pastoral areas or in typical mixed farming, was characterised by their integrated nature and the harmony with the environment. Animal numbers and production levels were mainly determined by the availability of feed resources either coming from natural vegetation, cultivated forages or from crop residues. Animal waste remained on site and nutrient outputs, contained in animal products that had left the system, were modest and well compensated by nutrient releases from mother rock and soils. The systems remained at equilibrium for centuries.
Industrial revolution, population growth and urbanisation came to break the equilibrium in these production systems. The Green Revolution technology, in particular, has caused specialisation in agriculture. It is greatly based, directly or indirectly, on the use of fossil fuel energy and has replaced human resources (oil for people). Higher crop and animal yields are obtained with large amounts of outside inputs (fertilisers, pesticides, feeds, etc) destined to satisfy the needs of rapidly growing urban centres, composed partly of the displaced rural labour force itself.
Post-war technological colonialism exported the intensive (industrial) animal production model, originally designed for industrialised countries, to developing countries, most of them in the tropics. These high input-output, land-detached systems are the "Green Revolution Technology" version for livestock production. Due to their rapid turnover, dependency on compounded feeds and high feed conversion efficiency, the emphasis for adoption of these systems was given to monogastric production.
Monogastrics, mainly poultry and swine, obtain essential nutrients (amino acids, vitamins and minerals) from oilseed meals (amino acid sources) complemented by minerals and premixes. The energy for this process comes from grains. Consequently, the major production cost is the feed, representing 70-80% of the total. The differential cost for shipping (dry) feedstuffs versus refrigerated/frozen meat (about 1:10) and the perishable nature of eggs, encourages export of raw materials rather than final products. An exception to this has been (dehydrated) powder milk which is easily exported from countries with low-cost (e.g. New Zealand) or subsidised production (e.g. USA, EU) to countries with unsatisfied demand (e.g. Indonesia, Malaysia, México).
Companies exporting the industrial animal production technology, and investors accepting it, were not concerned with animal wastes. Since these intensive units appeared quite suddenly, and they were supposed to provide inexpensive animal proteins, the society and the governments were not particularly prepared for the negative aspects of them either. The main interest from the producers (investors) was on rapid turnover and profit making derived from inexpensive inputs and favourable markets, but the environmental and social impacts were grossly overlooked. In the original countries of the industrial system, mainly in the USA, careful attention was paid to the collection, processing and disposal/recycling of excreted nutrients. However when these systems were exported to developing countries, the responsibility of the producer and the commercial companies finished at farm limits. It was up to the communities and the authorities to look after the issue beyond that point. Since in most cases regulations were lacking or, if existing, were not enforced, local pollution was allowed for a long time, and still is, in many areas.
In contrast with industrial systems, small-scale (family) units, which also proliferated in most cities taking advantage of free family labour, available feed resources and market proximity, have not had significant environmental impacts. Feeds come from crop residues, agro-industries, restaurant food wastes, market vegetable and animal rejects, slaughterhouse residues and commercial feed companies. Animal wastes are handled dry and disposed in agriculture fields or sold to fertilise nurseries and gardens. However, government and academic institutions have not shown much interest in this type of production. Under the current structure of value, there is little prestige (and economic incentive) to work for the less privileged sector, as opposed to helping and supporting wealthy owners and large corporations.
For various reasons related to the global environment (generation of greenhouse gases from fossil fuels), local environment (reduction of nutrient load), variable grain prices (constant risk of sudden price rise due to crop failure in exporting or importing countries), and concerns to reduce dependency (national food security), among others, it is desirable to look for alternative, more sustainable feeds and feeding systems based on local resources.
Current feeding systems in industrial production is based on grains and oil seed cakes, which in most cases are imported. In fact, there is an important movement of nutrients in feed (mainly N and P) from exporting to importing countries. However, this is small compared with the huge production and movement of mineral fertilisers. The world fertiliser production in 1995 (FAO, 1995) was 80.4 million tons for nitrogen, 32.8 million tons for phosphorus and 23.2 million tons for potassium.
Although some improvements are possible to increase efficiency and reduce environmental impact of land-detached systems based on compounded feeds, the challenge for the Area-Wide Integration (AWI) approach is to come up with alternative systems or modify and strengthen already existing ones which satisfy modern requirements. Such systems should be able to provide an adequate supply of animal products for a growing urban demand as well as be socially and environmentally acceptable. The latter implies an adequate recycling of nutrients.
There are alternative feeds and feeding systems for the various domestic species. The following list on feeds is in no way an exhaustive list, neither is it prioritised, but it does provide a few options to be considered for the various regions. More detailed scientific and technical information on these and other feeds can be obtained in the Feed Resources (FAO/AGA) Home Page on the Internet. A comprehensive technical and socio-economic analysis, together with an environmental impact assessment, need to be conducted for each alternative feeding system before it is included in extension or development plans.
1. Institutional (food) residues. Food waste (table and kitchen scraps) from restaurants and catering facilities of various institutions (e.g. schools, hospitals, companies, etc) can be collected, transported and processed into liquid or dry meal for feeding swine (Figueroa and Sanchez, 1997). Treatment is designed to eliminate common potential pathogens but temperature, pressure and time needed to destroy Bovine Spongiform Encephalopathy (BSE) can be accommodated if required. Due to energy costs for processing, it is preferable to produce a liquid product, which can be easily transported to swine farms and mixed with other ingredients to meet nutrient requirements. The amount of food residues that is currently wasted is huge and can make a significant contribution to swine production. Domestic food residues are more difficult to handle in quantities, but they are already being used to feed back-yard stock, mainly in peri-urban areas.
2. Industrial crop energy sources. Products of sugar cane (juice, various types of molasses, cachaza), oil palm (whole fruits, oil, fibre press by-product, fatty acids, etc) and cassava (chips) can be used to provide part or all the energy in the diet. The fact that these energy feedstuffs contain very little protein facilitates their complementation and helps to reduce nitrogen excretion. This will be discussed later.
1. Industrial crops can also provide products and by-products that can be utilised in poultry diets, replacing traditional ingredients. However, the anatomic nature of chickens and hens, and current building and crate designs do not facilitate the inclusion of a variety of feedstuffs that cannot be dried and milled. Many more options exist for ducks, which can be fed liquid and semi-liquid diets and can have levels of performance for egg and meat production comparable to those of hens and broilers.
2. Scavenging feed resources (SFR) under plantations. The historical feed base for poultry has been the scavenging feeds, which in many cases only poultry could harvest (e.g. worms, insects, etc.), often complemented by kitchen wastes , crop by-products and spare grains. In tree crop plantations (e.g. oil palm, rubber) there are a lot of SFR which remain mostly under-utilised but could be consumed by chickens, ducks, turkeys and geese, alone or in combinations. Some poultry production already exits, but taking into consideration the huge areas under plantation crops the potential is large. However, it requires a different form of vertical integration, perhaps similar to the one in Bangladesh with the growing interest in natural (organic) foods, animals reared under plantations could demand a premium price.
1. Cows and buffaloes are currently being fed with forages and crop residues complemented with agro-industrial by-products. The impressive increase of beef production in China based on treated (small-grain cereal straws) and conserved (sorghum and maize stalks) crop residues clearly shows the potential of this form of integration. Weaner calves coming from pasture lands or reared locally are finished in mixed farming areas where the above feed resources are available.
2. Forages in oil palm plantations. The carrying capacity of forages in oil palm plantations is just beginning to be utilised. The emphasis has been on beef cattle but there is also a potential for dairy animals if correctly supplemented. The cover crops (mixture of legumes) established to control weeds could be improved by including more palatable species.
1. Forages from plantations. Although direct grazing of small ruminants on forages under plantations has been attempted with relatively good success at the beginning, internal parasite challenges severely limit this approach. In contrast, manual cut-and-carry systems work extremely well and are culturally accepted in many countries.
2. High quality forages. A breakthrough on the feeding of small ruminants, particularly dairy goats, has come from the use of high quality forages, especially mulberry, which have similar nutritional values for ruminants as commercial concentrates. Considering the tradition and knowledge of mulberry planting (for silkworms) in many areas of Asia, one could envisage a viable intensive dairy production not only in mixed farming areas but also in some peri-urban units.
1. Vegetable wastes. At family level, small animals (rabbits, guinea pigs, snails, etc) can be fed with home and market vegetable residues making, in some cases, significant contributions to the economy and nutrition of peri-urban and rural households. A combination of adequate feeding (nutritious and inexpensive rations) and proper housing (e.g. underground shelters for rabbits in hot climates) is essential for successful production.
2. High quality forages. Although experimental evidence is still lacking, there are indications that small animals could be reared economically on diets based on high quality forages (e.g. mulberry, hibiscus, malvaviscus)
Although feed is the raw material for animal production anywhere, in the case of AWI schemes, environmental and health factors are the essential key factors for sustainability. Feeds can be transported from around the world, but animal waste must be treated and disposed off locally in a proper way to prevent negative ecological impacts. A recent hypothesis places animal health risk factors (microbial diseases) over environmental ones for determining the economic sustainability of high density industrial animal production in the medium and short terms, but it is beyond the scope of this paper to discuss this.
The waste generated in intensive animal production units is composed basically of three fractions: water, organic matter and inorganic matter (minerals). Water in itself does not cause any pollution, but is the vehicle for the other two fractions that do. If animal waste is handled and processed without adding extra water, it is bound to cause less problems. Poultry manure (chicken litter and poultry droppings) is not normally considered a problem. On the contrary, in most places, depending on the local legislation, it is a valuable feed ingredient or fertiliser. Cattle manure is rarely an environmental risk, unless large numbers of animals are concentrated in restricted areas far from agricultural fields. However, waste generated from swine units is seen as the main polluter of surface and ground water sources. Swine waste is in between poultry and cattle waste in terms of biological oxygen demand (BOD) and concentration of major nutrients (nitrogen and phosphorus), but pen and building design requires the use of water to flush out the waste and to clean the pens.
Once the waste is diluted with water, the whole treatment and decontamination process gets more complicated and, in many cases, impossible to carry out at reasonable costs. In many tropical environments, the problem with pig residuals gets more complicated as additional water is used to reduce heat load of animals or because of poor building design, rain water gets mixed with washing water.
There is, thus, an urgent need to design swine production systems and installations that require little or no water. Important considerations for the design of innovative swine facilities are: a) pigs are very clean animals, if given the opportunity they can quickly identify their "dirty" area; b) thermal regulation is essential for acceptable performance and pigs dissipate heat through conduction (contact with cooler surfaces) and water evaporation from their skin from bathing or wallowing (since pigs can not sweat); and c) wild pigs are nocturnal and sleep during the day in cool burrows or caves.
Measures to reduce, or to eliminate, waste pollution in swine industrial systems include the reduction of water consumption (if washing is needed, use high pressure hose), avoid mixing feed refusals with manure, formulation of diets for various groups of animals (phase feeding), use of synthetic amino acids to reduce total nitrogen content, use of enzymes to improve phosphates and starch digestion and use of energy sources low in protein.
The general strategy for waste treatment could include the following: 1) separation of solids (solids can be then composted or dried to be used as fertiliser, feed or energy source); 2) anaerobic digestion of the liquid fraction (biogas can be used for heating, drying or power generation); 3) use of digester effluent as fertiliser for crops (higher value than the raw slurry), or as feed/fertiliser for fish ponds and wetlands (with fast growing shrubs or trees); 4) mineral reduction with aquatic plants (water hyacinth, lemna); 5) aerobic digestion (oxidation) and reduction (to reduce nitrates to N2); and 6) the final water (low in BOD and minerals) can then be recycled for washing or irrigation. Under normal treatment conditions, it is very costly to clean the effluent well enough to be discharged into watercourses, but it can be done.
The two most important nutrients from the environmental point of view are currently nitrogen (N) and phosphorus (P), although metals can also be of concern in special circumstances. These nutrients come into the farm via fertilisers (N,P), feed (N,P), fixation (N), rainfall (N), runoff (N,P) and rock decomposition (P). They leave the farm in products, manure, effluents, compost, and through leaching and emissions (N). Depending on the level of intensification of agricultural practices and animal feeding, most of the nutrients come from fertilisers and feeds, and leave via products and leaching.
Globally, atmospheric N is synthesised naturally by soil microbes (N2 to ammonium compounds), mostly by the Rhizobium/legume association (plants absorb N as nitrates). Legume seeds containing essential amino acids (EAA) are used as food and feed (EAA source for monogastrics and N source for ruminants) after oil extraction. Legume foliage is used for feed (energy and N source for ruminants) or green manure (soil protection, fertiliser). Artificial fixation requires fossil fuels (coal, natural gas and oil) to produce N fertilisers (NH3, ammonium salts, urea), mostly for cereal crops. Cereal grains are used for food and feed (mainly as a source of energy). Cereal straw and stalks either decompose in situ (contributing to organic matter), or are burnt or used as feed for ruminants (a N source is required for their efficient digestion). Domestic animals (monogastrics and ruminants) produce high valued protein sources (eggs, meat, milk). Human and animal wastes are treated to reduce pathogens, BOD and nutrients, and the N is eventually recycled to other plants (ammonium compounds to nitrates) or reduced to N2 which goes back to the atmosphere. However, there are a lot of emissions of ammonia and nitrogen oxides, which cause serious environmental degradation due to the green gas effect, acid rain and ammonia deposition in water bodies.
Phosphate cycle is much simpler. Most of the phosphorus fertiliser comes from phosphate rocks mined in the USA, China, Morocco and Brazil. Once applied in the soil, P is fixed and does not move much, and is gradually taken up by plants. With continuous application of P fertilisers and manure, the P retention capacity is reached, and phosphates leach into ground and runoff waters, resulting in eutrophication. Phosphate eventually ends up in the sea.
Nutrient balances (specially for N and P) are now been calculated and monitored in livestock farms in some countries of the European Union (Groen and van Bruchem, 1996) and, in the future, nutrient balances will have to be kept if environmental pollution is to be reduced and controlled. On a national scale, guidelines have been published for green gas inventories (IPPC, 1995)
1. Market and technology will determine feeds and feeding systems in intensive animal production.
2. There will be a tendency to transport animal products rather than feedstuffs (raw materials), but it greatly depends on local conditions.
3. Waste treatment (environmental considerations) will determine size, type and location of intensive animal production. A sustainable system will have nutrient recycling (soil-crop-feed-animals-manure-soil).
1. A study on the movement of nutrients should be done at world level and a continuous monitoring programme should be established.
2. Nutrient balances should be kept at national, watershed and farm levels as required.
3. At farm level, nutrient flows should be monitored (using P as indicator), special attention should be given to potentially polluting heavy metals.
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Figueroa, Vilda y Sánchez, M.D. (1997). Tratamiento y utilización de residuos de origen animal, pesquero y alimenticio en la alimentación animal. Memorias Taller Instituto de Investigaciones Porcinas- FAO, La Habana, Cuba 5-8 spetiembre 1994. Estudio FAO Producción y Sanidad Animal 134.
Groen, A.F.and van Bruchem, J. (1996). Utilisation of local feed resources for dairy cattle: perspective for environmentally balanced production systems. Wageningen Institute of Animal Sciences, The Netherlands, EAAP Publication No. 84. 153p.
Intergovernmental Panel on Climate Change. (1995). Green Gas Inventory Reporting
Instructions. UNEP/WMO/OECD/IEA/IPCC, IPCC/WGI Technical Support Unit, Bracknell, UK.
Regional Workshop on Area-Wide Integration of Crop-Livestock Activities, 18-20 June, 1998, FAO Regional Office, Bangkok Thailand.
